Trane Failed Start/Run Capacitor

Trane outdoor unit makes a loud humming sound but the fan and compressor do not start.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Open or weak dual run capacitor, Loose capacitor terminals, Overheated capacitor from high ambient temperatures

How to Fix / Troubleshooting

Safety first: Turn off power at the disconnect and verify with a non-contact tester. Capacitors store energy; discharge them safely before handling.

  • Access capacitor: Remove the service panel and locate the metal can capacitor connected to the fan and compressor.
  • Visual check: Look for bulging top, rust, or oil leakage. Any deformation indicates failure.
  • Replace capacitor: Note the microfarad (µF) and voltage ratings and wiring positions (C, FAN, HERM). Replace with an identical Trane-approved or equivalent capacitor. Move one wire at a time to the new capacitor to avoid miswiring.
  • Secure mounting: Fasten the new capacitor firmly to prevent vibration damage.

Restore power and test. If the unit still only hums, the compressor or fan motor may also be failing and should be checked by a technician.

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Repair Difficulty

Medium 3/5

Required Part

Trane Dual Run Capacitor
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